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MarcR

9020 hydro question

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MarcR
Hi All, Trying to diagnose my 9020 hydro problem. Following symptoms: - Hydro has full power to about half way up the forward or reverse lever and then seems to ‘starve’ and the belts squeal. More noticeable on climbing grades or pushing snow. I think power is good at lower lever settings. - When using the front blade or blower up/down lever, power to the hydro is much weaker and the tractor slows down. I have replaced the trans fluid/filter, drive belts and checked clutch tension. I had to tighten the spring to almost 1” over spec (7 ¾”) to get the tractor to not squeal all the time, even at light grades with no load. Trying to go in 2nd or 3rd will always loose power, even at lower lever settings. I do not really have the capability to check hydro pressure, but am reasonably mechanically inclined. Any similar symptoms out there and perhaps some hints on where to look first? Is the main pump/hydro unit hard to diagnose/fix? Many thanks – great forum guys! Marc

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arnoldir
What type of filter did you use ? I bought a 720 that could ot climb a 4" curb in 1st gear and could not lift a box blade on the 3pt. an OEM Simp filter restored the tractor's performance to where it could spin the tires with he loader bucket down, and when cold the tractor lifts a 300lb box blade 12" off the ground in about 4 seconds. On this machine the filter is on the suction side and is supposed to be a minimum of 25 micron mesh.

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D-17_Dave
With a problem as you descibe, ie, pump is taking tremedous HP to run, as indicated by slipping the belts. But does operate at any engine rpm yet has'nt self destructed and implements are slow to pick up. Sounds to me like either the main trans. pump or the trans. motor is out. I work on a lot of Hydrostat. units and any major component that wears out and allows significant "leakage" overworks the charge pump which takes incredible HP to move the amount of oil reqiured to now operate the system. In otherwords, Bad problem in the hydro. I can go into more detail but I you said you did'nt have the test equipment and this needs to be rebuilt by pro's anyway, My advise is to remove the hydro and get it too the doc. The only other source of problem is the 2 bearings in the clutch by the drive pully siezing up onder losd after thy get hot. But you say it's slow to lift implements and pulls HP bad indicates hydro problems. Hope this helps, Dave.

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MarcR
Thanks for the responses everyone. The tractor will lift a snowblower fine (about 4 sec). That's a heavy unit! There is no 'slow lift' issue, but using the front lift when moving will slow the tractor considerably. Power is great in low gear, as long as the hydro lever is not pushed up passed half way. Anything over that and it will squeal/lose motion. There is no difference running hot/cold. Could this be a seized clutch pivot bushing, as mentioned in other posts? I hope it is, as the hydro seems a daunting (and expensive)task. Anyone who can guide me though the bushing test, repack and zerk retrofit would be much appreciated. Thanks again, Marc

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UCD
What brand Filter do you have. It has been proven many times that a cheap filter ie (fram) will cause these problems. Just because a filter fits does not mean that it is the correct one. Some manufactures cross numbers just on thread size and gasket size. There are other concerns that dictate fit, filter media micron size, anti backflow valves, preasure relief valves etc. If you can not get an OEM filter Wix and NAPA (made by Wix)are a good cross. If one of their Filters crosses to an application that filter number meets that MFG's specs.

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StanD
Marc: The bearings are available for the clutch shaft as well as pivot bushings. There is a spacer between the two bearings. When installing the bearings you must be sure to replace the spacer & when tightened up rap both ends of the shaft to releive the side load on the bearings. I have replaced many bad bearings, hopefully it has not taken out the shaft. I always use loctite on the shaft nut when doing this. Failure to remove side load will ruin the new bearings. StanD

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cranemech
Marc, Can you tell what is causing the squealing ? Are the belts shiny indicating slippage or can you feel if the tensioning pulley bearings are bad ? When you shift from fwd to rev do you "clutch" or just nuetral and then change directions ? The problem I had on my 620 was that the bushings were bound up on the shaft not allowing the belts to fully tension. Mine was bound so bad that after using the clutch the unit would not drive. I removed mine cleaned the shaft and bushings.There is a space between the bushings that I drilled and tapped to install a grease zerk (make sure that the zerk will not cause any interference problems)reinstall on the shaft and fill the cavity with grease. I would also check your suction hoses to make sure that there are no kinks or restrictions. If this is a preexisting problem could someone have changed hoses and kinked them. All I can think of right now. Later, Chad

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MarcR
Problem solved!! Phew - this took a while as well. When looking at the clutch pivot arm, the travel seemed fine as well as the pulley bearings. Everything spun well. Then I noticed that on the trannie coolant line side that the belt guards had some rubbing wear. After taking the belts etc off, it turns out that the belt guard was mounted to tight. When the cluch was released, the guard was rubbing against the top pulley and preventing the belts to tighten completely. Hence the belt slippage and related power loss! Glad to have this one solved as it was bugging me big time - especially trying to plow snow! Regards & thanks to all - great forum! Marc

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